Five days late but still no BFP

DP and I have been trying for our second baby for the last four months or so. Every month before now, my menstrual cycle has been like clockwork. Normally I have a bit of a show before it arrives on the exact day it's due (28 day cycle). However, I was due last Thursday and there is still absolutely no sign. I have tested three times now. Twice with cheaper tests and once last night with a ClearBlue digital. Where is it?! And at what point do I book a doctor's appointment?

Unfortunately a doctor will probably just send you on your way. All you can do is wait. It’s probably certain that you’re not pregnant but probably having a cycle where you haven’t ovulated or late ovulation. Are you temping at all? Do you know you’ve ovulated? I know it’s frustrating but all you can do is wait it out now. Try and focus your mind elsewhere. X

I know this is an unlikely thing to happen to most people but I was pretty regular with my cycles, they lasted between 25-26 days and I got a VERY faint positive 11 days past period due day (tested twice the 1st time). I get horrendous ovulation pains when I ovulate so I knew an approximate time when that was too. There may still be hope